This invention relates generally to analysis of samples by gas chromatography, and more particularly relates to the analysis of hydrocarbon samples by gas chromatography. Relevant patents include U.S. Pat. Nos. 3,201,922 (Villalobos, issued 8/24/65), 3,654,145 (Brunnock et al, issued 4/4/72), 4,204,952 (Snyder, issued 5/27/80), 4,234,315 (Scott, issued 11/18/80), 4,384,471 (Wentzel, issued 5/24/83), 4,446,105 (Dinsmore et al, issued 5/1/84), 4,534,207 (Szakasits et al, issued 8/13/85) and 4,577,492 (Holba et al, issued 3/25/86).
It is important to be able to analyze a hydrocarbon sample quickly and cheaply. This importance is particularly acute in the petrochemical and chemical industries. This is because there may be frequent changes in the composition of feedstocks employed in the various processes that are involved in either the petrochemical or chemical industries. This has created the need for an on-site instrument which can quickly provide an analysis of the feed and/or product composition during plant operation to ensure that the feed and product composition are within desired ranges. The failure at an early stage to recognize poor plant performance, which may result in out-of-specification products, can lead to a serious loss in economic revenues.
Prior art analysis has generally consisted of a combination of gas chromatography and analytical chemistry methods conducted in some central laboratory which is normally remote from the chemical or petrochemical plant. The employment of these two (gas chromatography and analytical chemistry) methods is usually a time consuming and expensive proposition. Further, it often results in a lengthy time period between the time when the sample is actually taken and when the results are made available to the plant. This may exacerbate any potential economic loss due to poor plant performance during this time.
These and other limitations and disadvantages of the prior art are overcome by the present invention, however, and improved gas chromatographic methods and apparatus are provided for analyzing hydrocarbon samples.